Add the salt, maple syrup, rosemary, thyme, bay leaves, peppercorns, and crushed garlic to a large heatproof bowl. Squeeze the juice from the orange half into the bowl and drop the rind in too, or halve a whole mandarin and add both halves.
Pour the boiling water over everything and stir for a few minutes until the salt and maple syrup are completely dissolved.
Let the brine cool to room temperature, or stir in a few handfuls of ice to cool it right away. Never pour warm brine over raw chicken.
Remove the giblets from the chicken. Place the chicken in a 4 quart bowl or stockpot that fits in your refrigerator, and add the giblets if you are saving them for bone broth.
Pour the cooled brine over the chicken, then add cold water until the chicken is just covered.
Cover the bowl and refrigerate for 4 to 24 hours, ideally overnight.
When you are ready to roast, preheat the oven to 425°F.
Lift the chicken out of the brine and pat it very dry inside and out with paper towels. There is no need to rinse it.
Pull the rosemary, thyme, orange, garlic, and bay leaves out of the brine and tuck them into the cavity of the chicken. Discard the brine and peppercorns.
Pat the giblets dry, seal them in a zip top bag, and refrigerate them for bone broth.
Set the chicken breast side up in a 9x13 glass baking dish. Gently loosen the skin over each side of the breast with your fingers, then push 43g (3 tbsp) of the softened butter under the skin on each side and press it out to spread it across the breast.
Stir together the garlic powder, onion powder, crushed rosemary, sage, and black pepper. Sprinkle it evenly over the dry skin and rub it in.
Pour the water into the bottom of the baking dish.
Roast uncovered at 425°F for 30 minutes, until the top is browned.
Turn the second 9x13 baking dish upside down over the top of the first as a lid, or cover tightly with foil. Reduce the oven to 325°F and roast for 1½ hours more, until an instant read thermometer reads at least 165°F in the thickest part of the breast and the innermost part of the thigh.
For crispier skin, remove the top dish for the last 5 minutes, switch the oven to broil, and watch closely so the skin does not burn.
Let the chicken rest for 15 minutes before carving. Save the drippings, carcass, skin, and cavity aromatics with the giblets for bone broth.